1. Field of the Invention
The present invention relates generally to a household blender of the type used for altering the consistency of and/or blending liquid and solid food and more particularly to a microprocessor-based control circuit for controlling energization of the blender drive motor.
2. Description of the Related Art
Traditional household blenders have an array of mechanical switches for speed selection. A selected speed switch is engaged and the blender operates at the selected speed until the operator pushes an off switch that mechanically disengages the speed switch. Some prior art blenders (such as those used in bars and restaurants for mixing frozen drinks) are equipped with a rotary timer which permits unattended operation for a limited period of time. In either case the user of a traditional blender, and in particular the home user, has difficulty obtaining consistent and repeatable results. The traditional blender retains no record of the previous blending cycle. Nor does the traditional blender display the duration of the blending cycle. The operator must rely on his or her memory and/or visual observation of the results to reproduce a successful blending operation.
Some aspects of traditional blender design also present a safety hazard. A traditional blender (not equipped with a timer) will continue to run if left unattended and therefore constitutes an obvious safety hazard. Blenders are not typically equipped with safety mechanisms that detect the proper installation of the blender jar. Operation of the blender motor at high speeds when unloaded, i.e., not connected to the blender jar, can present a hazard to the operator as well as damage to the blender motor.
A preferred embodiment of a programmable electronic blender is provided with a microprocessor-based circuit for control of the blender motor drive. The microprocessor may be incorporated into a micro-controller that includes programmable memory (PROM or EPROM) for retention of programmed instructions as well as random access memory (RAM) for recording previous blending cycles. The instructions and memory improve the user-friendliness and utility of the programmable electronic blender. For example, the instructions allow a particular blending cycle to incorporate more than one blending speed. Additionally, the programmable electronic blender will repeat a previous user-selected blending cycle recorded in memory. Programmed instructions provide elapsed and countdown timers that allow a user to monitor the elapsed time of the blending program or the time remaining to completion of the blending program, depending on the blending program selected. A display portion includes a liquid crystal display for indication of the blending cycle selected as well as the relevant elapsed or remaining times. The display and memory capabilities of the programmable electronic blender permit the user to achieve more consistent and reproducible results.
In accordance with an additional aspect of the present invention, the programmable electronic blender is provided with safety features that will not permit the blender motor drive to be activated unless the blender jar is properly installed to the blender base. The energy efficiency and safety of the programmable blender are improved by incorporation of instructions to stop blending upon expiration of a user-selected time and shut down completely after a pre-determined period of inactivity.
An object of the present invention is to provide a new and improved programmable electronic blender that permits the home user to produce consistent and repeatable blending results.
Another object of the present invention is to provide a new and improved programmable electronic blender that provides the user with enhanced safety and convenience.
These and other objects, features, and advantages of the invention will become readily apparent to those skilled in the art upon reading the description of the preferred embodiments, in conjunction with the accompanying drawings.